Actively-engageable movement-restriction mechanism for use with an annuloplasty structure

A method, comprising:

• providing an implant:
• shaped so as to define a lumen therethrough and a flexible strip disposed at least in part within the lumen of the implant, the strip having:
• a first end,
• a second end, and
• a plurality of recesses, and
• including a locking mechanism to which the first and second ends of the strip are coupled such that the strip defines a closed loop and a perimeter thereof which (a) shortens when the first end is advanced through the locking mechanism in a first direction and (b) expands when the first end is advanced in a second direction opposite the first direction;
• advancing the first end of the strip in first and second opposing directions with respect to the second end of the strip;
• maintaining a recess-engaging portion in a position in which the recess-engaging portion is not disposed in any of the plurality of recesses during the advancing;
• and
• restricting the advancing by facilitating active positioning of the recess-engaging portion in one of the plurality of recesses.